/***************************************************************
  SYS-SELECT.C

       This file contains Linux/i386/ILP32 implementation of
       __cpu_sys_select().

       PART OF : CPU - library .

       USAGE   : Internal only .

       Copyright (C) 2026  by Andrew V.Kosteltsev.
       All Rights Reserved.
 ***************************************************************/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <errno.h>
#include <poll.h>
#include <signal.h>
#include <stdlib.h>
#include <time.h>

#include <libmcpu.h>
#include <cpu-sysdeps.h>


__mpu_int64_t
__cpu_sys_select( struct __cpu_select_entry *entries, __mpu_uint64_t count,
                  const struct __cpu_timeval *timeout )
{
  struct pollfd   *pfds = (struct pollfd *)0;
  struct timespec  ts;
  struct timespec *pts = (struct timespec *)0;
  __mpu_uint64_t   i;
  time_t           sec;
  int              ret;

  if( count && !entries ) return( -(__mpu_int64_t)__MCPU_EINVAL );
  if( count > (__mpu_uint64_t)(size_t)-1 / sizeof( *pfds ) )
    return( -(__mpu_int64_t)__MCPU_EINVAL );

  if( timeout )
  {
    if( timeout->tv_sec < 0 || timeout->tv_usec < 0 || timeout->tv_usec > 999999 )
      return( -(__mpu_int64_t)__MCPU_EINVAL );

    sec = (time_t)timeout->tv_sec;
    if( (__mpu_int64_t)sec != timeout->tv_sec )
      return( -(__mpu_int64_t)__MCPU_EOVERFLOW );

    ts.tv_sec = sec;
    ts.tv_nsec = (long)( timeout->tv_usec * 1000 );
    pts = &ts;
  }

  if( count )
  {
    pfds = (struct pollfd *)calloc( (size_t)count, sizeof( *pfds ) );
    if( !pfds ) return( -(__mpu_int64_t)__MCPU_ENOMEM );
  }

  for( i = 0; i < count; ++i )
  {
    pfds[i].fd = entries[i].host_fd;
    pfds[i].events = 0;
    pfds[i].revents = 0;
    entries[i].revents = 0;

    if( entries[i].events & __CPU_SELECT_READ )   pfds[i].events |= POLLIN;
    if( entries[i].events & __CPU_SELECT_WRITE )  pfds[i].events |= POLLOUT;
    if( entries[i].events & __CPU_SELECT_EXCEPT ) pfds[i].events |= POLLPRI;
  }

  ret = ppoll( pfds, (nfds_t)count, pts, (const sigset_t *)0 );
  if( ret < 0 )
  {
    ret = -(__mpu_int64_t)__cpu_errno_from_host( errno );
    free( pfds );
    return( (__mpu_int64_t)ret );
  }

  for( i = 0; i < count; ++i )
  {
    short revents = pfds[i].revents;

    if( revents & POLLNVAL )
    {
      free( pfds );
      return( -(__mpu_int64_t)__MCPU_EBADF );
    }

    if( ( entries[i].events & __CPU_SELECT_READ ) &&
        ( revents & ( POLLIN | POLLHUP | POLLERR ) ) )
      entries[i].revents |= __CPU_SELECT_READ;

    if( ( entries[i].events & __CPU_SELECT_WRITE ) &&
        ( revents & ( POLLOUT | POLLERR ) ) )
      entries[i].revents |= __CPU_SELECT_WRITE;

    if( ( entries[i].events & __CPU_SELECT_EXCEPT ) && ( revents & POLLPRI ) )
      entries[i].revents |= __CPU_SELECT_EXCEPT;
  }

  free( pfds );
  return( 0 );

} /* End of __cpu_sys_select() */